Potentiation of biocide activity using diethanolamide

ABSTRACT

A method for increasing the effectiveness of a biocide is described. In the method, at least one biocide and at least one diethanolamide are applied to a substrate or aqueous system subject to the growth of microorganisms. The diethanolamide is applied in an amount effective to increase the biocidal activity of the biocide. Biocidal compositions are described where the biocide and the diethanolamide are present in a combined amount effective to control the growth of at least one microorganism. Methods for controlling the growth of microorganisms on various substrates and in various aqueous systems are also described. The combination of the biocide and the diethanolamide is particularly useful as a biocide in the leather industry, the lumber industry, the papermaking industry, the textile industry, the agricultural industry, and the coating industry, as well as in industrial process waters.

FIELD OF THE INVENTION

The invention relates to compositions and methods for controlling thegrowth of microorganisms on a variety of substrates and in aqueoussystems. More particularly, the invention relates to a combination of atleast one biocide with at least one diethanolamide where thediethanolamide potentiates the biocide's biocidal effect.

BACKGROUND OF THE INVENTION

A large variety of commercial, industrial, agricultural, and woodmaterials or products are subject to microbiological attack ordegradation which reduces or destroys their economic value. Examples ofsuch materials or products include surface coatings, lumber, seeds,plants, leather and plastics. The various temperatures at which suchmaterials or products are manufactured, stored, or used as well as theirintrinsic characteristics make them susceptible to growth, attack, anddegradation by common microorganisms such as algae, fungi, yeasts, andbacteria. These microorganisms may be introduced during manufacturing orother industrial process, by exposure to air, tanks, pipes, equipment,and humans. They can also be introduced while using a material orproduct, for example, by multiple openings and reclosures of packages orfrom stirring or removing material with contaminated objects.

Aqueous systems are also highly subject to microbiological growth,attack, and degradation. These aqueous systems may be fresh, brackish orsaltwater systems. Exemplary aqueous systems include, but are notlimited to, latexes, surfactants, dispersants, stabilizers, thickeners,adhesives, starches, waxes, proteins, emulsifying agents, celluloseproducts, metal working fluids, cooling water, waste water, processwater, aqueous emulsions, aqueous detergents, coating compositions,paint compositions, and resins formulated in aqueous solutions,emulsions or suspensions. These systems frequently contain relativelylarge amounts of water and organic material causing them to beenvironments well-suited for microbiological growth and thus attack anddegradation.

Microbiological degradation of aqueous systems may manifest itself as avariety of problems, such as loss of viscosity, gas formation,objectionable odors, decreased pH, emulsion breaking, color change, andgelling. Additionally, microbiological deterioration of aqueous systemscan cause fouling of the related water-handling system, which mayinclude cooling towers, pumps, heat exchangers, and pipelines, heatingsystems, scrubbing systems, and other similar systems.

Another objectionable phenomenon occurring in aqueous systems,particularly in aqueous industrial process fluids, is slime formation.Slime formation can occur in fresh, brackish or salt water systems.Slime consists of matted deposits of microorganisms, fibers and debris.It may be stringy, pasty, rubbery, tapioca-like, or hard, and may have acharacteristic undesirable odor that is different from that of theaqueous system in which it formed. The microorganisms involved in itsformation are primarily different species of spore-forming andnonspore-forming bacteria, particularly capsulated forms of bacteriawhich secrete gelatinous substances that envelop or encase the cells.Slime microorganisms also include filamentous bacteria, filamentousfungi of the mold type, yeast, and yeast-like organisms. Slime reducesyields in production and causes plugging, bulking, and other problems inindustrial water systems.

Various chemicals known as biocides have been used to preventmicrobiological deterioration of industrial systems, raw materials, andproducts. Examples of such biocides include:

TCMTB formulations, containing the fungicide2-(thiocyanomethylthio)-benzothiazole (TCMTB), which are known in theart and have often been used to control or prevent biological fouling,including biofilm and slime formation, in aqueous systems. TCMTB hasbeen used for industrial microorganism control for over 20 years. TCMTBis known to be useful in controlling bacteria and fungi in variousaqueous systems and is commercially available from Buckman Laboratories,Inc., Memphis, Tenn., under the tradenames BUSAN® 30WB and BUSAN® 1030as a 30% active ingredient. The preparation and use of2-(thiocyanomethyl-thio)-benzothiazole as a microbicide and apreservative is described in U.S. Pat. Nos. 3,520,976, 4,293,559,4,866,081, 4,595,691, 4,944,892, 4,839,373, and 4,479,961 give examplesof microbicidal properties of 2-(thiocyanomethylthio)benzothiazole. U.S.Pat. No. 5,413,795 describes compositions having TCMTB adsorbed onto asolid carrier. The disclosures of all of these patents are incorporatedherein by reference.

Kathon: a two component microbiocide mixture of5-chloro-2-methyl-4-isothiazolin-3-one (CMI) and2-methyl-4-isothiazolin-3-one (MI). Kathon is a broad spectrummicrobiocide used in the pulp and paper industry. Kathon is alsorecommended to control bacteria and fungi in water-based paper coatingsand coating components. Kathon is available from Rohm and Haas,Philadelphia Pa. and as BUSAN® 1078 from Buckman Laboratories, Memphis,Tenn. BUSAN® 1078 is contains 1.15% by weight of CMI and 0.35% by weightof MI as active ingredients. CMI and MI have the following chemicalstructures:

Bronopol: 2-bromo-2-nitropropane-1,3-diol. Bronopol is available asMYACIDE® from Angus Chemical Company, Northbrook, Ill. Bronopol is usedin water treatment, oil production fluids, waste injection wells, andwith pulp and paper. The chemical formula of bronopol is:

IPBC: Iodopropargyl butyl carbamate. IPBC can be obtained from TroyChemical, Newark, N.J. IPBC is an effective fungicide, particularly insurface coating compositions, such as paint formulations. IPBC isdisclosed in U.S. Pat. Nos. 3,923,870 and 5,219,875. IPBC has thefollowing chemical formula:

IPC: lodopropargyl carbamate. IPC, an effective microbiocide in aqueoussystems and on numerous substrates, is disclosed in U.S. Pat. Nos.4,945,109 and 5,328,926. The chemical formula of IPC is:

DBNPA: 2,2-Dibromo-3-nitrilopropionamide. DBNPA is available from DowChemical Company, Midland, Mich. and Buckman Laboratories, Memphis,Tenn. as the product BUSAN® 94. DBNPA is a broad spectrum bactericidehaving particular use to control slime in the pulp and paper industry.BUSAN® 94 contains 20% by weight of DBNPA as its active ingredient.DBNPA has the chemical structure:

Tribromophenol: 2,4,6-Tribromophenol. Tribromophenol is an antifungalagent available from Great Lakes Chemical, West Lafayette, Ind. underthe trade name GREAT LAKES PH-73. The chemical formula of tribromophenolis:

BIT: 1,2-benzisothiazoline-3-one. 1,2-Benzisothiazoline-3-one is abiocide useful for a variety of aqueous systems, such as metalworkingfluids, paint, adhesives, starch-based-products, cellulose ethersolutions, resin and rubber emulsions. 1,2-benzisothiazoline-3-one isavailable from ICI Specialty Chemicals, Melbourne, Australia as theproduct PROXEL GXL-20, an aqueous solution of dipropylene glycol 20% byweight of 1,2-benzisothiazoline-3-one as the active ingredient.1,2-Benzisothiazoline-3-one has the following chemical structure:

Propiconazole, also known as(RS)-1-2-[(2,4-dichlorophenyl)-2-propyl-1,3-dioxalan-2ylmethyl]-1H-1,2,4-triazole,is one commercial biocide which has been shown to have a reasonably goodtoxicological profile and biocidal activity. Propiconazole iscommercially available from Buckman Laboratories, Inc., Memphis, Tenn.,for example, as a formulation containing about 24% actives under thetradename BUSAN® 1292. Propiconazole has the following chemicalstructure:

Other biocides include potassium N-hydroxymethyl-N-methyl thiocarbamate,a 30% active ingredient in BUSAN® 52 product and2-bromo-4′-hydroxyacetophenone, a 30% active ingredient in BUSAN® 90.These products are available from Buckman Laboratories, Memphis, Tenn.

Despite the existence of such biocides, industry is constantly seekingmore cost-effective technology which offers equal or better protectionat lower cost and lower concentration. The concentration of conventionalbiocides and the corresponding treatment costs for such use, can berelatively high. Important factors in the search for cost-effectivefungicides include the duration of biocidal effect, reducedenviromnental impact, the ease of use and the effectiveness of thebiocide per unit weight.

SUMMARY OF THE INVENTION

In view of industry's search for more cost effective biocides, theinvention offers an improvement over current products or practices.

The invention relates to a method to increase the effectiveness of abiocide. This method applies at least one biocide and at least onediethanolamide to a substrate or aqueous system subject to the growth ofmicroorganisms. The diethanolamide is applied in an amount effective toincrease the biocidal activity of the biocide. The combination of thebiocide with a diethanolamide achieves superior biocidal activity atlower concentrations and lower cost than the biocide alone againstmicrobiological attack or degradation such as discussed above.

One embodiment of the invention provides a biocidal composition. Thecomposition contains (a) at least one biocide and (b) at least one fattyacid diethanolamide. In the composition, the biocide (a) and thediethanolamide (b) are present in a combined amount effective to controlthe growth of at least one microorganism.

Another embodiment of the invention provides a method for controllingthe growth of a microorganism on a substrate. This method contacts asubstrate susceptible to the growth of microorganisms with at least onebiocide and a diethanolamide. The biocide and diethanolamide are presentin a combined amount effective to control the growth of at least onemicroorganism on the substrate.

The combination of biocide and diethanolamide according to the inventionmay be used for controlling the growth of microorganisms in aqueoussystems. Thus, another embodiment of the invention provides a method forcontrolling the growth of microorganisms in an aqueous system capable ofsupporting growth of a microorganism. This method treats the aqueoussystem with at least one biocide and at least one diethanolamide above.The biocide and the diethanolamide are present in a combined amounteffective to control the growth of at least one microorganism in theaqueous system.

The biocide and diethanolamide combination of the invention is useful inpreventing the microbiological attack, degradation, or deterioration ofvarious types of raw materials and products such as leather, textiles,pulp, paper and paperboard, coatings, lumber, as well as agriculturalproducts such as seeds and crops. Advantageously, the combination may beused in various industrial processes used to prepare or manufacturethese products. Accordingly, additional embodiments of the inventionemploy the combination to control the growth of microorganisms on or insuch industrial products, raw materials or processes.

The foregoing and other features and advantages of the invention will bemade more apparent from the following detailed description and preferredembodiments.

DETAILED DESCRIPTION OF THE INVENTION

The invention relates to a method to increase the effectiveness of abiocide. This method applies at least one biocide and at least onediethanolamide to a substrate or aqueous system subject to the growth ofmicroorganisms. The diethanolamide is applied in an amount effective toincrease the biocidal activity of the biocide.

According to the invention, the combination of a biocide and adiethanolamide demonstrates an unexpected, enhanced biocidal effect.That is, the combination of a biocide and a diethanolamide achievessuperior biocidal activity at lower biocide concentrations as comparedto the biocidal capability of the biocide alone, although the amount ofdiethanolamide used has no biocidal effect itself. Thus, thediethanolamide potentiates the biocidal activity of the biocide. Such asuperior effect presents a distinct economic advantage and increases anindividual biocide's effectiveness per unit weight.

According to the invention, a diethanolamide may be used to increase theeffectiveness of any biocide or a mixture of biocides. Preferredbiocides include potassium N-hydroxymethyl-N-methyl thiocarbamate,2-thiocyanomethylthiobenzothiazole, propiconazole,2-bromo-4′-hydroxyacetophenone, sodium 2-mercaptobenzothiazole andmixtures thereof. The diethanolamide may be used with and in the samemanner as the particular biocide is used. Preferably, one or morediethanolamides are incorporated into the formulation of the biocide.

In one embodiment, the invention relates to a biocidal compositioncomprising at least one biocide and at least one diethanolamide. Thebiocide and the diethanolamide are present in a combined amounteffective to control the growth of at least one microorganism. Mixturesof diethanolamides may also be used.

A general synthesis of diethanolamides mixes a 1:1 molar ratio ofdiethanolamine with a fatty acid or mixture of fatty acids. The mixtureis then heated at a reflux under vacuum for several hours and water isremoved. If a mixture of acids is used, an averaged molecular weight iscalculated based on the ratio of individual acids in the mixture.Completion of the reaction can be monitored by IR analysis or free fattyacid content.

Fatty acids are carboxylic acids derived from or contained in an animalor vegetable fat or oil. Fatty acids are composed of a chain of alkylgroups containing from about 4 to about 22 carbon atoms (usually evennumbered) and have a terminal carboxylic acid group. Fatty acids may bestraight or branched, saturated or unsaturated and even aromatic. Fattyacids which may be used in the preparation of the diethanolamideinclude, but are not limited to, butyric acid, lauric acid, decanoicacid, undecylenic acid, palmitic acid, stearic acid, palmitoleic acid,oleic acid, isooleic acid, linoleic acid, linolenic acid, and phenylstearic acid. Fatty acids employed in this invention preferably havelong alkyl chains in the C₁₂-C₂₂ range, with C₁₆-C₂₀ being preferred.Unsaturated fatty acids such as oleic, isooleic, linoleic, and linolenicare preferred.

Mixtures of fatty acids may also be used in the preparation of mixturesof diethanolamide. For example, tall oil fatty acids, palm oil fattyacids, and coconut oil fatty acids are mixtures of fatty acids which maybe used to prepare a mixture of diethanolamides. Tall oil fatty acid(TOFA), which is predominantly a mixture of oleic acid (˜45 wt. %) andlinoleic acid (˜36 wt. %) and other fatty acids, is available fromArizona Chemical Company, Panama City, Fla. Another mixture of fattyacids is sold under the trade name Century MO-5 by Union Camp ChemicalCompany of Jacksonville, Fla. The Century MO-5 fatty acid mixturecontains about 46 wt. % isooleic acid, 37 wt. % oleic acid and 17 wt. %of saturated fatty acids such as palmitic acid and stearic acid.Mixtures of fatty acids represent a preferred embodiment of theinvention.

Depending on the application, biocidal compositions according to theinvention may be prepared in various forms known in the art. Forexample, the composition may be prepared in liquid form as an aqueoussolution, dispersion, emulsion, or suspension, a dispersion orsuspension in a non-solvent, or as a solution by dissolving the biocideand the diethanolamide in a solvent or combination of solvents. Suitablesolvents include, but are not limited to, methyl ethers of glycols,M-pyrol, or petroleum distillates. The biocidal composition may beprepared as a concentrate for dilution prior to its intended use. Commonadditives such as surfactants, emulsifiers, dispersants, and the likemay be used as known in the art to increase the solubility of thebiocide or diethanolamide in a liquid composition or system, such as anaqueous composition or system. In many cases, the biocidal compositionof the invention may be solubilized by simple agitation.

Biocidal compositions of the invention may also be prepared in solidform, for example as a powder or tablet, using means known in the art.In a preferred method of preparation, a liquid product containing thebiocide is deposited on a carrier such as diatomaceous earth or kaolinand mixed with a diethanolamide in the form of a liquid or solution toform a powder or tablet.

The biocide and the diethanolamide may be combined in a singlecomposition. Alternatively, the biocide and the diethanolamide may beemployed as separate components such that the combined amount for theintended use is effective to control the growth of at least onemicroorganism.

As discussed above, the diethanolamide potentiates the biocidal effectof the biocide. Thus, combining a diethanolamide with a biocide providessuperior biocidal activity to control the growth of microorganisms ascompared to the biocidal capability of the biocide alone. Although thediethanolamide may exhibit biocidal activity at concentrations abovecertain threshold levels, the diethanolamide is not biocidally effectiveat the concentrations used.

According to the invention, control of the growth of a microorganism ona substrate or in an aqueous system means control to, at, or below adesired level and for a desired period of time for the particularsubstrate or system. This can vary from the complete prevention orinhibition of microbiological growth to control at a certain desiredlevel and for a desired time. The combination of biocide anddiethanolamide described here can, in many cases, reduce the totalmicrobiological count to undetectable limits and maintain the count atthat level for a significant period of time. Accordingly, thecombination may be used to preserve a substrate or system.

The effective amount or percentage of the combination of a biocide and adiethanolamide necessary to achieve the desired result will varysomewhat depending on the substrate or aqueous system to be protected,the conditions for microbial growth, the particular biocide, and thedegree of protection desired. For a particular application, the amountof choice may be determined by routine testing of various amounts priorto treatment of the entire affected substrate or system. In general, aneffective amount used on a substrate ranges from about 0.0001% to about4% (w/w); preferably about 0.0001% to about 0.2%. With aqueous systems,an effective amount may range from about 0.5 to about 5000 parts permillion, more preferably from about 5 to about 1000 parts per million ofthe aqueous system, and most preferably from, about 10 to about 25 partsper million. Similar amounts effectively control slime formation. Forslime control, effective amounts preferably range from about 1 to about200 parts per million, and more preferably, from about 1 to about 25parts per million of the aqueous system, and in some cases as low as 0.5ppm.

In a preferred embodiment, combinations of a biocide and adiethanolamide are those combinations having a weight ratio of biocideto diethanolamide from about 99:1 to about 1:99. More preferably theweight ratio is from about 60:10 to about 10:60, and most preferably,from about 50:50 to about 25:75. The weight ratio may vary depending onthe biocide, the intended use, the microorganism encountered as well asthe particular material, product, or system to which the combinationaccording to the invention is applied.

The combination of a biocide and a diethanolamide may be applied in avariety of industrial uses and processes for microorganism control. Thecombination may be used in place of and in the same manner as otherbiocides traditionally used in the particular industry. As discussedabove, such industries include, but are not limited to the leatherindustry, the lumber industry, the papermaking industry, the textileindustry, the agricultural industry, and the coating industry. Thecombination of a biocide and a diethanolamide may also be used withaqueous systems such as those previously discussed which are subject tomicrobiological attack and degradation. The problems caused bymicrobiological attack and deterioration in these various applicationshas been described above. The use of the combination of a biocide and adiethanolamide according to the invention to control the growth ofmicroorganisms in particular exemplary applications is described below.

The invention also relates to a method for controlling the growth ofmicroorganisms on various substrates. The method comprises the step ofcontacting a substrate susceptible to microbiological growth or attackwith a biocide and a diethanolamide, as described above. The biocide anddiethanolamide are present in a combined amount effective to control thegrowth of at least one microorganism on the substrate. Preferably, themethod may be used to eliminate or prevent substantially allmicrobiological growth on the substrate. As discussed above, the biocideand the diethanolamide may be applied together or as separatecompositions. Preferred applications of this general method arediscussed below.

In the leather industry, the combination of a biocide and adiethanolamide may be used to control the growth of microorganisms on ahide during a tanning process. To achieve this control, the hide iscontacted with a combined amount of a biocide and a diethanolamideeffective to control the growth of at least one microorganism on thehide. The combination of the biocide and the diethanolamide may be usedin the tanning process in similar amounts and manner similar to thatused to apply other biocides used in the tanning industry. The type ofhide may be any type of hide or skin that is tanned, for examplecowhide, snake skin, alligator skin, sheep skin, and the like. Theamount used, to some extent, will depend on the degree ofmicrobiological resistance required and may be readily determined by oneskilled in the art.

A typical tanning process comprises a number of stages, including, butnot limited to, a pickling stage, a chrome-tanning stage, avegetable-tanning stage, a post-tan washing stage, a retaining stage, adyeing stage, and a fatliquoring stage. The combination of a biocide anda diethanolamide may be used during all process stages in the tanningprocess in addition to those stages where a known microbiologicalproblem is occurring. In each stage, the combination of a biocide and adiethanolamide may be a component of the appropriate tanning liquorapplied to the hide undergoing tanning.

Incorporating the biocide and a diethanolamide in a tanning liquorprotects the hide from microbiological deterioration during the tanningprocess. Preferably, the combination is uniformly dispersed, e.g., underagitation, into an appropriate liquor to be used in a tanning process.Typical tanning liquors include, for example, a pickling liquor, achrome-tanning liquor, a vegetable-tanning liquor, a post-tan washingliquor, a retanning liquor, a dye liquor, and a fatliquor. This methodof application ensures that the combination applied to the hidesprotects against microbiological attack, deterioration, or othermicrobiological degradation.

In a somewhat analogous nature, the combination of the invention mayalso be employed to control the growth of microorganisms on a textilesubstrate in a textile manufacturing process. Contacting the textilesubstrate with a combination of a biocide and a diethanolamide accordingto the invention effectively controls the growth of a microorganism onthe textile substrate. In a textile process, the combination may be usedin similar amounts and a manner similar to other biocides commonly usedin such processes. As one of ordinary skill would appreciate, particularamounts generally depend on the textile substrate and the degree ofmicrobiological resistance required.

The step of contacting the textile substrate with the combination of abiocide and a diethanolamide may be accomplished using means known inthe textile art. To control microbiological growth, a textile processgenerally dips the textile substrate into a bath containing a biocide,alone or with other chemicals used to treat the textile substrate.Alternatively, the textile substrate may be sprayed with a formulationcontaining a biocide. In the bath or the spray, the combination ofbiocide and diethanolamide according to the invention are present in acombined amount effective to control the growth of at least onemicroorganism on the textile substrate. Preferably, the bath and thespray are aqueous-based compositions.

To preserve the value of its raw materials and products, the lumberindustry also must control the growth of microorganisms in order toprevent microbiological degradation of lumber. The combination of abiocide and a diethanolamide according to the invention is effective tocontrol the growth of microorganisms on lumber.

The combination of a biocide and a diethanolamide may be used to protectthe lumber in similar amounts and a similar manner employed for otherbiocides used in the lumber industry. Contacting lumber with aneffective amount of the combination may be accomplished, for example, byspraying the lumber with an aqueous formulation containing thecombination of a biocide and a diethanolamide, by dipping the lumberinto a dip bath containing the combination, or other means known in theart. Dipping the lumber in an aqueous bath is preferred.

The biocide and the diethanolamide are preferably uniformly dispersed ina bath (for example, by agitation) prior to the dipping of the lumberinto the bath. In general, the lumber is dipped into the bath, raised,allowed to drip dry, and then air dried. The dip time will depend, as isknown in the art, on a variety of factors such as the biocide, thedegree of microbiological resistance desired, the moisture content ofthe lumber, type and density of the wood, etc. Pressure may be appliedto promote penetration of the combination into the lumber being treated.Applying a vacuum to the upper surface of the lumber may also be used todegas the lumber and promote increased wetting of the lumber by a bathcontaining the biocidal combination.

The combination of a biocide and a diethanolamide according to theinvention also has uses in the agricultural industry. To control thegrowth of microorganisms on a seed or plant, the seed or plant may becontacted with a biocide and a diethanolamide in a combined amounteffective to control the growth of at least one microorganism on theseed or plant. This contacting step may be accomplished using means andamounts known in the agricultural industry for other biocides. Forexample, the seed or plant may be sprayed with an aqueous formulationcontaining the combination of biocide and diethanolamide, or dipped intoa bath containing the combination. After being sprayed or dipped, theseed or plant is generally dried by means known in the art such as dripdrying, heated drying, or air drying. For plants or crops, thecombination may also be applied using a soil drench. Soil drenching isparticularly advantageous when the microorganisms of concern inhabit thesoil surrounding the plant.

Yet another aspect of the invention is a method for controlling thegrowth of microorganisms in an aqueous system capable of supporting suchgrowth. The aqueous system is treated with a biocide and adiethanolamide such that the biocide and diethanolamide are present in acombined amount effective to control the growth of at least onemicroorganism in the aqueous system. This includes controlling, andpreferably preventing, slime formation in the aqueous system.

Examples of various aqueous systems include, but are not limited to,latexes, surfactants, dispersants, stabilizers, thickeners, adhesives,starches, waxes, proteins, emulsifying agents, cellulose products,aqueous emulsions, aqueous detergents, coating compositions, paintcompositions, alum compositions, and resins formulated in aqueoussolutions, emulsions or suspensions. The combination may also beemployed in aqueous systems used in industrial processes such as metalworking fluids, cooling waters (both intake cooling water and effluentcooling water), and waste waters including waste waters or sanitationwaters undergoing treatment of the waste in the water, e.g., sewagetreatment.

As with the other uses discussed above, the combination of a biocide anda diethanolamide according to the invention may be used in the sameamounts and in the same manner as biocides traditionally used in thesevarious aqueous systems. The combination not only protects the aqueoussystem prior to use or when stored, but in many cases protects theaqueous system when in use or in appropriate applications even after theaqueous system has dried. When used in a paint formulation for example,the combination not only protects the paint in the can, but also thepaint film after being applied to a substrate.

Another embodiment of the invention is a method for controlling thegrowth of microorganisms on paper or in a papermaking process, e.g., ina pulp or paper slurry and on a finished paper product such as paperboard. The paper, pulp, or slurry is contacted with a biocide and adiethanolamide in a combined amount effective to control the growth ofat least one microorganism on the paper, the pulp or in a slurry. Thecontacting step is accomplished using means and amounts known in thepapermaking art.

According to this aspect of the invention, for example, a forming web ona papermaking machine (or a wet-lap pulp) may be contacted with thecombination of a biocide and a diethanolamide by spraying an aqueousdispersion containing the biocide and diethanolamide onto the pulp afterthe pulp leaves the presses in a papermaking process. Or, the biocideand the diethanolamide may be incorporated into a bath used at the wetor size press and the web contacted by nipping the web to incorporatethe combination into the web with any other agents applied at the press.Alternatively, the pulp may be contacted by mixing the biocide anddiethanolamide into the pulp/white water mixture, preferably prior tothe pulp reaching the formation wire.

When treating paper (which includes paperboard and other cellulosicproducts or substrates), the biocide and diethanolamide may be addedinto pulp slurries in the headbox, in the substrate forming solution, orin the white water system to treat the water system itself or forincorporation into the body of the paper. Alternatively, as with otherknown biocides, the combination of a biocide and a diethanolamideaccording to the invention may be mixed into a coating used to coat thefinished paper.

The activity of the combinations described above has been confirmedusing standard laboratory techniques as discussed below. In many cases,the diethanolamide potentiates the biocidal affect of the particularbiocide. The following examples are intended to illustrate, not limit,the invention.

EXAMPLES

Preparation of N,N-Diethanol Tall Oil Fatty Acid Amide

1.24 moles of tall oil fatty acid (350 grams, 282 grams/mole) were addedwith 1.24 mole diethanolamine (130 grams, 105.14 grams/mole) to a threeneck round bottom flask equipped with a stirrer. The mixture was heatedat reflux under vacuum for several hours. Aliquots were removed todetect formation of amide peak by IR to monitor completion of thereaction.

Potentiating Effect of Diethanolamides

The following materials and procedure were used to determine thepotentiating effect of a diethanolamide with various biocides.

Materials

1. Microorganisms

(1) Pseudomonas aeruginosa (“Ps. aeruginosa”) ATCC 15442 (a bacterium)

(2) Aspergillus niger (“A. niger”) ATCC 9642 (a fungus).

2. Biocides

(1) potassium N-hydroxymethyl-N-methyl thiocarbamate, a 30% activeingredient in BUSAN® 52 product;

(2) 2-thiocyanomethylthiobenzothiazole as BUSAN® 1030;

(3) 24% active propiconazole as BUSAN® 1292; and

(4) 2-bromo-4′-hydroxyacetophenone as BUSAN® 90.

3. Diethanolamides

(1) N,N-diethanol tall oil fatty amide; and

(2) diethanolamide of Century MO-5.

4. Growth Media

(1) Antibacterial Test:

NaCl, 8.0 g; glucose, 1.0 g; tryptone, 1.0 g; DI water, 1.0 L.

(2) Antifungal Test:

KH₂PO₄, 0.7 g; MgSO₄ 7H₂O, 0.7 g; MnSO₄7H₂O, 1.0 mg;

NaCl, 5.0 mg; FeSO₄ 7H₂O, 2.0 mg; ZnSO₄ 7H₂O, 2.0 mg;

NH₄NO₃, 1.0 g; Glucose, 10.0 g; DI Water, 1.0 L.

Procedure

5 ml of growth medium were suspended in test tubes, and the culturemedium was autoclaved at 121° C. for 20 min. Biocide stock aqueoussolutions were added in each tube to give the desiredbiocide-diethanolamide concentrations in parts per million. No biocidewas added to the control tubes. All tubes were inoculated by adding 0.1ml of inoculum to give a bacterial concentration of about 10⁶ cells/ml(10⁶ spores/ml for fungal test). After each addition, the tubes wereshaken vigorously to mix the contents thoroughly. All inoculated tubeswere placed at 37° C. for antibacterial test and at 28° C. forantifungal test. Bacterial growth was checked after 5-7 days and fungalgrowth was checked after 10-14 days.

The MIC of each biocide and diethanolamide acting alone and incombination was determined on a growth-no-growth basis. Tables 1-16present both the lowest concentrations of each biocide anddiethanolamide separately for which there was no growth, and the lowestconcentration of biocide in combination with diethanolamide for whichthere was no growth. A plus (+) sign represents the presence of fugal orbacterial mat and a minus (−) sign represents the absence of fungal orbacterial mat. The only tables which demonstrate a neutral effect areTables 2 and 4 where both diethanolamide of Century MO-5 andN,N-diethanol tall oil fatty amide had a neutral effect against Ps.aeruginosa. This is due to the fact that propiconazole does not have anyantibacterial activity within the concentration range tested, i.e., upto 2000 ppm.

TABLE 1 Combination of BUSAN ® 1292 with diethanolamide of Century MO-5against A. niger BUSAN ® Diethanol- BUSAN ® Diethanol- 1292 amide 1292amide (ppm) (ppm) Growth (ppm) (ppm) Growth 5  0 + 20 10 + 10   0 + 2020 + 20   0 + 20 50 + 40   0 + 20 100  + 60   0 + 20 200  + 80   0 − 20500  + 0 10 + 40 10 + 0 20 + 40 20 + 0 50 + 40 50 + 0 100  + 40 100  + 0200  + 40 200  − 0 500  + 40 500  − 5 10 + 60 10 − 5 20 + 60 20 − 5 50 +60 50 − 5 100  + 60 100  − 5 200  + 60 200  − 5 500  + 60 500  − 10 10 + 80 10 − 10  20 + 80 20 − 10  50 + 80 50 − 10  100  + 80 100  − 10 200  + 80 200  − 10  500  + 80 500  −

TABLE 2 Combination of BUSAN ® 1292 with diethanolamide of Century MO-5against Ps. aeruginosa BUSAN ® Diethanol- BUSAN ® Diethanol- 1292 amide1292 amide (ppm) (ppm) Growth (ppm) (ppm) Growth 100  0 + 500 10 + 200 0 + 500 20 + 500  0 + 500 50 + 800  0 + 500 100  + 1000   0 + 500200  + 2000   0 + 500 500  +  0 10 + 800 10 +  0 20 + 800 20 +  0 50 +800 50 +  0 100  + 800 100  +  0 200  + 800 200  +  0 500  + 800 500  +100 10 + 1000  10 + 100 20 + 1000  20 + 100 50 + 1000  50 + 100 100  +1000  100  + 100 200  + 1000  200  + 100 500  + 1000  500  + 200 10 +2000  10 + 200 20 + 2000  20 + 200 50 + 2000  50 + 200 100  + 2000 100  + 200 200  + 2000  200  + 200 500  + 2000  500  +

TABLE 3 Combination of BUSAN ® 1292 with N,N-diethanol tall oil fattyamide against A. niger BUSAN ® Diethanol- BUSAN ® Diethanol- 1292 amide1292 amide (ppm) (ppm) Growth (ppm) (ppm) Growth  5  0 + 20 10 + 10  0 +20 20 + 20  0 + 20 50 + 40  0 + 20 100  + 60  0 + 20 200  + 80  0 − 20500  +  0 10 + 40 10 −  0 20 + 40 20 −  0 50 + 40 50 +  0 100  + 40100  +  0 200  + 40 200  +  0 500  + 40 500  −  5 10 + 60 10 −  5 20 +60 20 −  5 50 + 60 50 −  5 100  + 60 100  −  5 200  + 60 200  −  5500  + 60 500  − 10 10 + 80 10 − 10 20 + 80 20 − 10 50 + 80 50 − 10100  + 80 100  − 10 200  + 80 200  − 10 500  + 80 500  −

TABLE 4 Combination of BUSAN ® 1292 with N,N-diethanol tall oil fattyamide against Ps. aeruginosa BUSAN ® Diethanol- BUSAN ® Diethanol- 1292amide 1292 amide (ppm) (ppm) Growth (ppm) (ppm) Growth 100  0 + 500 10 + 200  0 + 500  20 + 500  0 + 500  50 + 800  0 + 500 100 + 1000  0 + 500 200 + 2000   0 + 500 500 +  0 10 + 800  10 +  0 20 + 800  20 + 0 50 + 800  50 +  0 100  + 800 100 +  0 200  + 800 200 +  0 500  + 800500 + 100 10 + 1000   10 + 100 20 + 1000   20 + 100 50 + 1000   50 + 100100  + 1000  100 + 100 200  + 1000  200 + 100 500  + 1000  500 − 20010 + 2000   10 − 200 20 + 2000   20 − 200 50 + 2000   50 − 200 100  +2000  100 + 200 200  + 2000  200 + 200 500  + 2000  500 +

TABLE 5 Combination of BUSAN ® 1030 with diethanolamide of Century MO-5against A. niger BUSAN ® Diethanol- BUSAN ® Diethanol- 1030 amide 1030amide (ppm) (ppm) Growth (ppm) (ppm) Growth 0.25  0 + 0.75 10 − 0.50 0 + 0.75 20 − 0.75  0 − 0.75 50 − 1  0 − 0.75 100  − 2  0 − 0.75 200  −0.75 500  − 0 10 + 1 10 − 0 20 + 1 20 − 0 50 + 1 50 − 0 100  + 1 100  −0 200  + 1 200  − 0 500  + 1 500  − 0.25 10 + 2 10 − 0.25 20 + 2 20 −0.25 50 + 2 50 − 0.25 100  + 2 100  − 0.25 200  + 2 200  − 0.25 500  + 2500  − 0.50 10 − 0.50 20 − 0.50 50 − 0.50 100  − 0.50 200  − 0.50 500  −

TABLE 6 Combination of BUSAN ® 1030 with diethanolamide of Century MO-5against Ps. aeruginosa BUSAN ® Diethanol- BUSAN ® Diethanol- 1030 amide1030 amide (ppm) (ppm) Growth (ppm) (ppm) Growth 10  0 + 40 10 + 20  0 +40 20 − 40  0 + 40 50 − 80  0 − 40 100  − 160   0 − 40 200  + 40 500  + 0 10 + 80 10 −  0 20 + 80 20 −  0 50 + 80 50 −  0 100  + 80 100  −  0200  + 80 200  −  0 500  + 80 500  − 10 10 + 160  10 − 10 20 + 160  20 −10 50 + 160  50 − 10 100  + 160  100  − 10 200  + 160  200  − 10 500  +160  500  − 20 10 + 20 20 + 20 50 − 20 100  − 20 200  − 20 500  +

TABLE 7 Combination of BUSAN ® 1030 with N,N-diethanol tall oil fattyamide against A. niger BUSAN ® Diethanol- BUSAN ® Diethanol- 1030 amide1030 amide (ppm) (ppm) Growth (ppm) (ppm) Growth 0.20  0 + 0.5  1 + 0.50 0 + 0.5  5 + 1  0 − 0.5 10 − 2  0 − 0.5 25 − 4  0 − 0.5 50 − 0.5 100  +0  1 + 1  1 − 0  5 + 1  5 − 0 10 + 1 10 − 0 25 + I 25 − 0 50 + 1 50 − 0100  + 1 100  − 0.2  1 + 2  1 − 0.2  5 + 2  5 − 0.2 10 + 2 10 − 0.2 25 +2 25 − 0.2 50 + 2 50 − 0.2 100  + 2 100  −

TABLE 8 Combination of BUSAN ® 1030 with N,N-diethanol tall oil fattyamide against Ps. aruginosa BUSAN ® Diethanol- BUSAN ® Diethanol- 1030amide 1030 amide (ppm) (ppm) Growth (ppm) (ppm) Growth 10  0 + 40  1 +20  0 + 40  5 + 40  0 + 40 10 − 80  0 − 40 25 − 160   0 − 40 50 − − 40100  −  0  1 + 80  1 −  0  5 + 80  5 −  0 10 + 80 10 −  0 25 + 80 25 − 0 50 + 80 50 −  0 100  + 80 100  − 10  1 + 160   1 − 10  5 + 160   5 −10 10 + 160  10 − 10 25 + 160  25 − 10 50 + 160  50 − 10 100  + 160 100  − 20  1 + 20  5 + 20 10 + 20 25 + 20 50 + 20 100  +

TABLE 9 Combination of BUSAN ® 52 with diethanolamide of Century MO-5against A. niger BUSAN ® Diethanol- BUSAN ® Diethanol- 52 amide 52 amide(ppm) (ppm) Growth (ppm) (ppm) Growth 5  0 +  20  10 + 10   0 +  20 20 + 20   0 +  20  50 − 50   0 −  20 100 − 100   0 −  20 200 − 200   0−  20 500 − 0 10 +  50  10 − 0 20 +  50  20 − 0 50 +  50  50 − 0 100  + 50 100 − 0 200  +  50 200 − 0 500  +  50 500 − 5 10 + 100  10 − 5 20 +100  20 − 5 50 + 100  50 − 5 100  + 100 100 − 5 200  + 100 200 − 5500  + 100 500 − 10  10 + 200  10 − 10  20 + 200  20 − 10  50 + 200  50− 10  100  + 200 100 − 10  200  + 200 200 − 10  500  + 200 500 −

TABLE 10 Combination of BUSAN ® 52 with diethanolamide of Century MO-5against Ps. aeruginosa BUSAN ® Diethanol- BUSAN ® Diethanol- 52 amide 52amide (ppm) (ppm) Growth (ppm) (ppm) Growth 10  0 +  50 10 + 20  0 +  5020 + 50  0 +  50 50 − 100   0 +  50 100  − 200   0 −  50 200  + 400   0−  50 500  +  0 10 + 100 10 +  0 20 + 100 20 −  0 50 + 100 50 −  0100  + 100 100  −  0 200  + 100 200  −  0 500  + 100 500  + 10 10 + 20010 − 10 20 + 200 20 − 10 50 + 200 50 − 10 100  + 200 100  − 10 200  +200 200  − 10 500  + 200 500  − 20 10 + 400 10 − 20 20 + 400 20 − 2050 + 400 50 − 20 100  + 400 100  − 20 200  + 400 200  − 20 500  + 400500  −

TABLE 11 Combination of BUSAN ® 52 with N,N-diethanol tall oil fattyamide against A. niger BUSAN ® 52 Diethanolamide (ppm) (ppm) Growth 50 + 10 0 + 20 0 + 50 0 − 100 0 − 200 0 − 0 10 + 0 20 + 0 50 + 0 100 + 0200 + 0 500 + 5 10 + 5 20 + 5 50 + 5 100 + 5 200 + 5 500 + 10 10 + 1020 + 10 50 + 10 100 + 10 200 + 10 500 + 20 10 − 20 20 − 20 50 − 20 100 −20 200 − 20 500 + 50 10 − 50 20 − 50 50 − 50 100 − 50 200 − 50 500 − 10010 − 100 20 − 100 50 − 100 100 − 100 200 − 100 500 − 200 10 − 200 20 −200 50 − 200 100 − 200 200 − 200 500 −

TABLE 12 Combination of BUSAN ® 52 with N,N-diethanol tall oil fattyamide against Ps. aeruginosa BUSAN ® 52 Diethanolamide (ppm) (ppm)Growth 10 0 + 20 0 + 50 0 + 100 0 + 200 0 − 400 0 − 0 10 + 0 20 + 0 50 +0 100 + 0 200 + 0 500 + 10 10 + 10 20 + 10 50 + 10 100 + 10 200 + 10500 + 20 10 + 20 20 + 20 50 + 20 100 + 20 200 + 20 500 + 50 10 + 50 20 +50 50 + 50 100 + 50 200 + 50 500 + 100 10 − 100 20 − 100 50 − 100 100 −100 200 − 100 500 − 200 10 − 200 20 − 200 50 − 200 100 − 200 200 − 200500 − 400 10 − 400 20 − 400 50 − 400 100 − 400 200 − 400 500 −

TABLE 13 Combination of BUSAN ® 90 with diethanolamide of Century MO-5against A. niger BUSAN ® 90 Diethanolamide (ppm) (ppm) Growth 2.5 0 + 50 + 10 0 + 20 0 − 40 0 − 80 0 − 0 10 + 0 20 + 0 50 + 0 100 + 0 200 + 0500 + 2.5 10 + 2.5 20 + 2.5 50 + 2.5 100 + 2.5 200 + 2.5 500 + 5 10 + 520 − 5 50 − 5 100 + 5 200 + 5 500 + 10 10 + 10 20 + 10 50 − 10 100 − 10200 − 10 500 + 20 10 − 20 20 − 20 50 − 20 100 − 20 200 − 20 500 − 40 10− 40 20 − 40 50 − 40 100 − 40 200 − 40 500 − 80 10 − 80 20 − 80 50 − 80100 − 80 200 − 80 500 −

TABLE 14 Combination of BUSAN ® 90 with diethanolamide of Century MO-5against Ps. aeruginosa BUSAN ® 90 Diethanolamide (ppm) (ppm) Growth 50 + 10 0 + 20 0 + 40 0 + 80 0 − 160 0 − 0 10 + 0 20 + 0 50 + 0 100 + 0200 + 0 500 + 5 10 + 5 20 + 5 50 + 5 100 + 5 200 + 5 500 + 10 10 + 1020 + 10 50 + 10 100 + 10 200 + 10 500 + 20 10 + 20 20 + 20 50 + 20 100 +20 200 + 20 500 + 40 10 + 40 20 + 40 50 + 40 100 + 40 200 − 40 500 − 8010 − 80 20 − 80 50 − 80 100 − 80 200 − 80 500 − 160 10 − 160 20 − 160 50− 160 100 − 160 200 − 160 500 −

TABLE 15 Combination of BUSAN ® 90 with N,N-diethanol tall oil fattyamide against A. niger BUSAN ® 90 Diethanolamide (ppm) (ppm) Growth 2.50 + 5 0 + 10 0 + 20 0 − 40 0 − 80 0 − 0 1 + 0 5 + 0 10 + 0 20 + 0 50 + 0100 + 2.5 1 + 2.5 5 + 2.5 10 + 2.5 20 + 2.5 50 + 2.5 100 + 5 1 + 5 5 + 510 + 5 20 + 5 50 + 5 100 + BUSAN ® 52 Diethanolamide (ppm) (ppm) Growth10 1 + 10 5 + 10 10 + 10 20 − 10 50 − 10 100 − 20 1 − 20 5 − 20 10 − 2020 − 20 50 − 20 100 − 40 1 − 40 5 − 40 10 − 40 20 − 40 50 − 40 100 − 801 − 80 5 − 80 10 − 80 20 − 80 50 − 80 100 −

TABLE 16 Combination of BUSAN ® 90 with N,N-diethanol tall oil fattyamide against Ps. aeruginosa BUSAN ® 90 Diethanolamide (ppm) (ppm)Growth 5 0 + 10 0 + 20 0 + 40 0 + 80 0 − 160 0 − 0 1 + 0 5 + 0 10 + 025 + 0 50 + 0 100 + 5 1 + 5 5 + 5 10 + 5 25 + 5 50 + 5 100 + 10 1 + 105 + 10 10 + 10 25 + 10 50 + 10 100 + 20 1 + 20 5 + 20 10 + 20 25 + 2050 + 20 100 + 40 1 + 40 5 + 40 10 − 40 25 − 40 50 − 40 100 − 80 1 − 80 5− 80 10 − 80 25 − 80 50 − 80 100 − 160 1 − 160 5 − 160 10 − 160 25 − 16050 − 160 100 −

The claimed invention is:
 1. A method to increase the effectiveness of abiocide comprising the step of applying at least one biocide and atleast one diethanolamide of a C₁₂-C₂₂ fatty acid to a substrate oraqueous system subject to the growth of microorganisms, wherein saiddiethanolamide is applied in an amount effective to increase thebiocidal activity of the biocide, wherein said biocide is potassiumN-hydroxymethyl-N-methyl thiocarbamate,2-thiocyanometylthiobenzothiazole, propiconazole,2-bromo-4′-hydroxyacetophenone, sodium 2-mercaptobenzothiazole or amixture thereof.
 2. A method according to claim 1, wherein said C₁₂-C₂₂fatty acid comprises stearic acid, palmitic acid, oleic acid, isooleicacid, linoleic acid, or a mixture thereof.
 3. A method according toclaim 1, wherein said C₁₂-C₂₂ fatty acid diethanolamide is anN,N-diethanol tall oil fatty amide; diethanolamides of a mixture offatty acids comprising isooleic acid, oleic acid, palmitic acid andstearic acid; or a mixture thereof.
 4. A method according to claim 1,wherein the weight ratio of biocide to diethanolamide ranges from about99:1 to about 1:99.
 5. A method according to claim 4, wherein saidweight ratio ranges from about 60:10 to about 10:60.
 6. A methodaccording to claim 5, wherein said weight ratio ranges from about 50:50to about 25:75.
 7. A method for controlling the growth of microorganismson a substrate comprising the step of contacting a substrate susceptibleto the growth of microorganisms with (a) at least one biocide; and (b)at least one diethanolamide of a C₁₂-C₂₂ fatty acid, and wherein (a) and(b) are present in a combined amount effective to control the growth ofat least one microorganism on said substrate, wherein said biocide ispotassium-N-hydroxymethyl-N-methyl thiocarbamate,2-thiocyanomethylthiobenzothiazole, propiconazole,2-bromo-4′-hydroxyacetophenone, sodium 2-mercaptobenzothiazole or amixture thereof.
 8. A method according to claim 7, wherein said C₁₂-C₂₂fatty acid diethanolamide is an N,N-diethanol tall oil fatty amide;diethanolamides of a mixture of fatty acids comprising isooleic acid,oleic acid, palmitic acid and stearic acid; or a mixture thereof andsaid microorganism is selected from algae, fungi, and bacteria.
 9. Amethod of claim 7, wherein said substrate is a hide, a textilesubstrate, lumber, a seed, or a plant.
 10. A method according to claim7, wherein said combined amount ranges from about 0.0001% to about 4% byweight, based upon the total weight of the substrate.
 11. A methodaccording to claim 10, wherein said combined amount ranges from about0.0001% to about 0.2%.
 12. A method for controlling the growth ofmicroorganisms in an aqueous system capable of supporting growth of amicroorganism comprising the step of treating said aqueous system with(a) at least one biocide, and (b) at least one diethanolamide of aC₁₂-C₂₂ fatty acid and wherein (a) and (b) are present in a combinedamount effective to control the growth of at least one microorganism,wherein said biocide comprises potassium N-hydroxymethyl-N-methylthiocarbamate, 2-thiocyanomethylthiobenzothiazole, propiconazole,2-bromo-4′-hydroxyacetophenone, sodium 2-mercaptobenzothiazole or amixture thereof.
 13. A method according to claim 12, wherein saidC₁₂-C₂₂ fatty acid diethanolamide is an N,N-diethanol tall oil fattyamide; diethanolamides of a mixture of fatty acids comprising iso-oleicacid, oleic acid, palmitic acid and stearic acid; or a mixture thereof.14. A method according to claim 12, wherein said microorganism isselected from algae, fungi, and bacteria.
 15. A method according toclaim 12, wherein said aqueous system is a latex, a metal working fluid,an aqueous emulsion, an aqueous detergent, cooling water, or an aqueousresin formulation.
 16. A method according to claim 12, wherein saidcombined amount ranges from about 0.5 to about 5000 parts per million ofthe aqueous system.
 17. A method according to claim 16, wherein saidcombined amount ranges from about 5 to about 1000 parts per million ofthe aqueous system.
 18. A method according to claim 17, wherein saidcombined amount ranges from about 10 to about 25 parts per million ofthe aqueous system.
 19. A method for controlling the growth ofmicroorganisms on pulp or paper in a papermaking process, comprising thestep of contacting the pulp or paper with (a) at least one biocide, and(b) at least one diethanolamide of a C₁₂-C₂₂ fatty acid and wherein (a)and (b) are present in a combined amount effective to control the growthof at least one microorganism, wherein said biocide potassiumN-hydroxymethyl-N-methyl thiocarbamate,2-thiocyanomethylthiobenzothiazole, propiconazole,2-bromo-4′-hydroxyacetophenone, sodium 2-mercaptobenzothiazole or amixture thereof.
 20. A method according to claim 19, wherein said pulpis contacted by mixing said biocide and said diethanolamide into a pulpslurry prior to reaching a formation wire in a papermaking process. 21.A method according to claim 19, wherein said C₁₂-C₂₂ fatty aciddiethanolamide is an N,N-diethanol tall oil fatty amide; diethanolamidesof a mixture of fatty acids comprising iso-oleic acid, oleic acid,palmitic acid and stearic acid; or a mixture thereof.
 22. A methodaccording to claim 19, wherein said microorganism is selected fromalgae, fungi, and bacteria.